The small molecule NS11021 is a potent and specific activator of Ca2+-activated big-conductance K+ channels

Mol Pharmacol. 2007 Oct;72(4):1033-44. doi: 10.1124/mol.107.038331. Epub 2007 Jul 16.

Abstract

Large-conductance Ca(2+)- and voltage-activated K(+) channels (Kca1.1/BK/MaxiK) are widely expressed ion channels. They provide a Ca(2+)-dependent feedback mechanism for the regulation of various body functions such as blood flow, neurotransmitter release, uresis, and immunity. In addition, a mitochondrial K(+) channel with KCa1.1-resembling properties has been found in the heart, where it may be involved in regulation of energy consumption. In the present study, the effect of a novel NeuroSearch compound, 1-(3,5-bis-trifluoromethyl-phenyl)-3-[4-bromo-2-(1H-tetrazol-5-yl)-phenyl]-thiourea (NS11021), was investigated on cloned KCa1.1 expressed in Xenopus laevis oocytes and mammalian cells using electrophysiological methods. NS11021 at concentrations above 0.3 microM activated KCa1.1 in a concentration-dependent manner by parallel-shifting the channel activation curves to more negative potentials. Single-channel analysis revealed that NS11021 increased the open probability of the channel by altering gating kinetics without affecting the single-channel conductance. NS11021 (10 microM) influenced neither a number of cloned Kv channels nor endogenous Na(+) and Ca(2+) channels (L- and T-type) in guinea pig cardiac myocytes. In conclusion, NS11021 is a novel KCa1.1 channel activator with better specificity and a 10 times higher potency compared with the most broadly applied KCa1.1 opener, NS1619. Thus, NS11021 might be a valuable tool compound when addressing the physiological and pathophysiological roles of KCa1.1 channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cell Line
  • Guinea Pigs
  • Humans
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / agonists*
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / genetics
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / physiology
  • Mice
  • Mice, Knockout
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Tetrazoles / pharmacology*
  • Thiourea / analogs & derivatives*
  • Thiourea / pharmacology
  • Xenopus laevis

Substances

  • 1-(3,5-bis(trifluoromethyl)phenyl)-3-(4-bromo-2-(1H-tetrazol-5-yl)phenyl)thiourea
  • Kcnma1 protein, mouse
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
  • Tetrazoles
  • Thiourea
  • Calcium